1. Field of the Invention
The present invention relates to an improvement in or relating to an earthquake-resistant door structure which can be opened even if the wall or door frame is deformed by a strong force applied thereto when an earthquake occurs or when a strong wind blows. Also, the present invention relates to an earthquake-resistant device which can be fixed to a door having 5 to 6 millimeter-wide clearances between the lateral or longitudinal side of the door and the corresponding lateral or longitudinal side of the surrounding door frame, no matter what type of lock the door may have fixed thereto, rim type or mortise type, assuring that the door can be opened no matter what extensive or localized deformation may be caused in the wall or surrounding door frame.
2. Description of Related Art
When a strong earthquake occurs, buildings are broken or so badly deformed that doors could not open to confine people in rooms. People will be panic-stricken, and sometimes people can not leave closed rooms, getting involved in fires or collapse when happening subsequent to the earthquake as a secondary disaster. Therefore, there has been an ever increasing demand for earthquake-resistant door, which have means to assure the opening of the door even if the door frames are badly deformed as a result of earthquake.
Kobe district was stricken by such a great earthquake that nobody had experienced before (called "the Great Earthquake in the Hanshin District"), and people have learnt that doors should be so resistant to earthquake as to permit people to open the doors even if the door frames are badly deformed. Earthquake-resistant doors are assured to be reliable if they pass the performance test of doors (particularly, the resistance-to-diagonal deformation test under static load, and resistance-to-localized deformation test under static load) according to the residential articles checking guidance which was officially prescribed in July, 1996.
There are two kinds of locks commonly used in middle- or high-storied apartment houses, that is, rim type locks and mortise type locks. No matter which type of locks may be used, however, it may be possible that locks cannot be opened without being fixed to such earthquake-resistant doors as meet prescriptions both of resistance to diagonal deformation and resistance to localized deformation.
Japanese Utility Model 61-32072(B) shows such an earthquake-resistant door structure. Referring to FIG. 16, an earthquake-proof device comprises a two-rolled assembly 20 and a right-angled piece 21. The two-rolled assembly 20 has vertical and horizontal rolls 22 and 23 journaled by its bearing projections, and the right-angled piece 21 is chamfered on one lateral-and-longitudinal side. The two-rolled assembly 20 is fixed to the upper corner of the door on its rear side, and the right-angled piece 21 is fixed to the corresponding upper corner of the door frame with the chamfered edge directed outward. When the door is closed, the vertical and horizontal rolls 22 and 23 of the two-rolled assembly 20 are apart more or less from the lateral and longitudinal flat planes 24 of the right-angled piece 21. The vertical and/or horizontal rolls, however, are allowed to roll on the flat-and-slants of the lateral-and-vertical sections of the right-angled piece 21 only when the door is tilted in the door frame as a result of earthquake, thus permitting the door to be opened automatically.
Advantageously this earthquake-proof device can be fixed to not only a new door but also an existing door. The earthquake-proof device, however, need to be fixed to the door within a minimum allowance; if not, the door cannot be opened. Therefore, the fixing of such earthquake-proof devices to existing doors must rely on artisans, skillfulness.
Also, disadvantageously the earthquake-proof device when fixed to the door will spoil the pleasing appearance of the door. The door having such an earthquake-proof device is liable to give a negative impression of the door being defective more or less (the door appearing to be incomplete by itself unless such an extra device is attached), thus lowering the commercial quality.
Further, according to a recent commercialized earthquake-resistant door structure which has cleared said newly prescribed earthquake-resistant performance test, a gap of 13 mm is provided between the shutting style side end of the door body and the door frame. However, disadvantageously such a door structure requires extra parts such as dust- or wind-proof strips to cover the gap.